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'[EE] Home etched PCBs'
2010\12\21@184046 by Oli Glaser

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With the subject of home or in-house produced PBCs coming up the other day, I thought I would post these pictures I found of a little board I did a while back, just in case anyone is interested (or maybe thinks this kind of stuff is impossible)
The footprint is a 0.4mm pitch, 64 pin, QFN (tracks are down to 0.2mm IIRC)
Sorry the quality is so bad but hopefully one can get the general idea (it was taken with a phone camera through a loupe as my decent camera charger was broken at the time.. :-)  )
Unfortunately I have no pics of the board after it was populated (it worked okay though), and I can't locate the board (if I do I will post a pic)

http://s740.photobucket.com/albums/xx46/oliglaser/

2010\12\21@194748 by Jonathan Hallameyer

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What masking method and etching chemicals did you use?   Guessing
photo-resist and not toner transfer :o)

-Jon

On Tue, Dec 21, 2010 at 6:40 PM, Oli Glaser <spam_OUToli.glaserTakeThisOuTspamtalktalk.net> wrote:
{Quote hidden}

>

2010\12\21@203907 by Oli Glaser

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On 22/12/2010 00:47, Jonathan Hallameyer wrote:
> What masking method and etching chemicals did you use?   Guessing
> photo-resist and not toner transfer :o)
>
> -Jon

You guessed correct :-)
I usually use Fotoboard (positive resist coating) from Mega (very good
site for PCB stuff), which has always produced excellent results.
Artwork is produced with a 600/1200 dpi laser printer (proper HP
cartridge capable of producing sharp/dark lines) onto tracing paper. I
have used transparancy film but tracing paper is cheaper and just as
good. If I was doing this more often I would probably invest in a better
printer capable of up to 2400 dpi or so for the really small stuff, but
600 dpi does okay.
Etching chemicals are Ferric chloride (standard pellets) and Sodium
Metasilicate (ten times better than Sodium Hydroxide for development)
The main thing I have noticed is that *far* better results are produced
when board is agitated well in hot (between about 40 - 60 degrees, up to
70 okay IIRC) etching solution. Board etches far quicker (5 mins or so)
and sharper traces with less undercutting produced, which means thinner
traces can be made with less chance of breaks. A tank (can be expensive,
though some half decent ones can be found for less than £50 - ebay etc)
is an easy way to do this and takes most of the hassle and mess out of
the process (though similar results can be produced with just a tray)


2010\12\22@122859 by V G

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On Tue, Dec 21, 2010 at 6:40 PM, Oli Glaser <.....oli.glaserKILLspamspam@spam@talktalk.net> wrote:

> With the subject of home or in-house produced PBCs coming up the other
> day, I thought I would post these pictures I found of a little board I
> did a while back, just in case anyone is interested (or maybe thinks
> this kind of stuff is impossible)
> The footprint is a 0.4mm pitch, 64 pin, QFN (tracks are down to 0.2mm IIRC)
> Sorry the quality is so bad but hopefully one can get the general idea
> (it was taken with a phone camera through a loupe as my decent camera
> charger was broken at the time.. :-)  )
> Unfortunately I have no pics of the board after it was populated (it
> worked okay though), and I can't locate the board (if I do I will post a
> pic)
>
> http://s740.photobucket.com/albums/xx46/oliglaser/
>
>
Beautiful results. I'll probably stop doing toner transfer and do the photo
resist method

2010\12\22@170633 by Nathan House

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I would like to try the photoresist method sometime, too. Isn't it
more expensive than the toner transfer method, though? (As far as the
cost per-board, and also having to build the UV lightbox..).

For now I'm getting pretty good results with the toner transfer method:

www.roboticsguy.com/tutorials-/electronics-/pcb-/making-pcbs-toner-transfer-/images/l297-l298-printed-circuit-board-pcb-diy.jpg
http://www.roboticsguy.com/tutorials-/electronics-/pcb-/making-pcbs-toner-transfer-/images/pcb-traces-close.jp

2010\12\22@173948 by IVP

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> I usually use Fotoboard (positive resist coating) from Mega
> (very good site for PCB stuff), which has always produced
> excellent results

Oli, one of my Things To Do in the New Year is to try and find a
local supplier for Riston film and see if it's possible to make my own
photo-resist board. I've a very good friend in the laminating caper
who might be able to pull some strings. And possibly get chummier
with my board house to maybe get useable panel scraps. Hand-
drawing etch-resist is OK for prototypes and one-offs but printing
would be much more convenient

Jo

2010\12\22@174744 by Oli Glaser

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On 22/12/2010 22:06, Nathan House wrote:
> I would like to try the photoresist method sometime, too. Isn't it
> more expensive than the toner transfer method, though? (As far as the
> cost per-board, and also having to build the UV lightbox..).
>
> For now I'm getting pretty good results with the toner transfer method:
>
> www.roboticsguy.com/tutorials-/electronics-/pcb-/making-pcbs-toner-transfer-/images/l297-l298-printed-circuit-board-pcb-diy.jpg
> http://www.roboticsguy.com/tutorials-/electronics-/pcb-/making-pcbs-toner-transfer-/images/pcb-traces-close.jpg

It's not really much more expensive, and the UV box is a one time expense (you can buy a UV box on eBay for <£50, or even an old sun lamp will do - I used a £5 lamp to do a few boards ages ago, and it worked fine)
The PCB laminates cost a little more than plain board, not much though.
In any case, the expense is not really the reason for me, it's the ability to make a quick test board when I need it rather than wait a week for one from a PCB house. Most of the time I can wait though as I have plenty to do in the meantime.
Even for hobby purposes I'm not sure whether it's worth it from a savings point of view, given the very cheap prices you can get double sided prototypes done for nowadays. Spirit Circuits (UK) even do a free service for double sided with no resist/silk.

Everything else aside though, if you want to get the best possible results, photoresist is definitely the way to go. However, if you are intending to stick with through hole or larger pitch SMD, I would carry on as you are as your results look pretty good.

2010\12\22@175549 by Mark Rages

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On Tue, Dec 21, 2010 at 5:40 PM, Oli Glaser <oli.glaserspamKILLspamtalktalk.net> wrote:
> Unfortunately I have no pics of the board after it was populated (it
> worked okay though), and I can't locate the board (if I do I will post a
> pic)

That's the problem with these small parts: they make the board easy to lose..

Regards,
Mark
markrages@gmail
-- Mark Rages, Engineer
Midwest Telecine LLC
.....markragesKILLspamspam.....midwesttelecine.co

2010\12\22@180458 by Dwayne Reid

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At 03:06 PM 12/22/2010, Nathan House wrote:

>For now I'm getting pretty good results with the toner transfer method:
>
>www.roboticsguy.com/tutorials-/electronics-/pcb-/making-pcbs-toner-transfer-/images/l297-l298-printed-circuit-board-pcb-diy.jpg
>http://www.roboticsguy.com/tutorials-/electronics-/pcb-/making-pcbs-toner-transfer-/images/pcb-traces-close.jpg

I'd say that you are getting darned good results!

I'll make a suggestion, if I might.

I would edit your footprints to have much smaller holes.  You need only enough of a hole for the drill bit to center itself within.

I would think that soldering components to your PCB would be fairly difficult because of the amount of area where there is no solder.

Just a suggestion . . .

dwayne

-- Dwayne Reid   <EraseMEdwaynerspam_OUTspamTakeThisOuTplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
http://www.trinity-electronics.com
Custom Electronics Design and Manufacturing

2010\12\22@181653 by Oli Glaser

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On 22/12/2010 22:55, Mark Rages wrote:
> On Tue, Dec 21, 2010 at 5:40 PM, Oli Glaser<oli.glaserspamspam_OUTtalktalk.net>  wrote:
>> Unfortunately I have no pics of the board after it was populated (it
>> worked okay though), and I can't locate the board (if I do I will post a
>> pic)
> That's the problem with these small parts: they make the board easy to lose.
>

Lol, though it probably has more to do with my organisational skills (or lack of them) :-)
It's probably lurking in the back of drawer somewhere... (or sometimes I just chuck them if they will have no future use)
That is a problem with electronics though - so many tiny little parts to keep track of...

2010\12\22@183422 by Oli Glaser

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On 22/12/2010 22:39, IVP wrote:
>> I usually use Fotoboard (positive resist coating) from Mega
>> (very good site for PCB stuff), which has always produced
>> excellent results
> Oli, one of my Things To Do in the New Year is to try and find a
> local supplier for Riston film and see if it's possible to make my own
> photo-resist board. I've a very good friend in the laminating caper
> who might be able to pull some strings. And possibly get chummier
> with my board house to maybe get useable panel scraps. Hand-
> drawing etch-resist is OK for prototypes and one-offs but printing
> would be much more convenient
>
> Joe

Sounds like a good idea, I'd be interested to hear how you get on there. Pretty sure printing rather than hand drawing will save you a fair bit of time.
I've often thought about ways of making the PCB (prototyping) process easier/cheaper/quicker - got a few ideas but no time to explore them at present (that's always the problem.. too many ideas/too little time.. :-)  )

2010\12\22@193401 by Dwayne Reid

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At 03:39 PM 12/22/2010, IVP wrote:

>Oli, one of my Things To Do in the New Year is to try and find a
>local supplier for Riston film and see if it's possible to make my own
>photo-resist board.

Keep in mind that laminating the film to the PCB stock takes some work unless you have specialized laminating equipment.

We have a much-modified GBC laminator that uses heated rollers.  It was purchased from one of the PCB manufacturing equipment suppliers (don't recall just who right now) who apparently purchased these laminators from GBC by the truck-load, did their modifications, then sold them at highly inflated prices.  GBC, by the way, is General Binding Corporation.

We were lucky enough to purchase ours from one of the local technical universities who were upgrading.  It uses 12" wide film rolls and a 13" wide paper carrier for laminating single-sided boards or two 12" wide film rolls for laminating double-sided boards.

We had a multi-step cleaning process that we put the raw board through before applying the laminate.  Omit any of the cleaning steps: reliability went down.  Do all of the steps: the photo exposure gauge that we used said that we were getting something like 6 micron resolution on the copper.  Every time.

Yeah - Riston film really is that good.

Drilling the boards was done on a home-made contraption that used two stepper motors on a slanted MDF board setup in an arrangement that was derived from old-style drafting machines that a draftsman would use.  Both motors turn one direction: the board goes up and down.  Both motors turn in opposite directions: the board goes left and right.  The drill head was stationary and just moved up and down at the appropriate times.

It was fairly slow - perhaps one hole every 2 or 3 seconds.  But it was able to operate unattended except for bit changes and therefore quite reasonable for the time.

I can't take any credit for the drilling machine - it was built by Gordon Robineau from somewhere in the USA.  I found out about it in one of Don Lancaster's articles and purchased it directly from Gordon.  Gordon was also nice enough to release all of the documentation, including all mechanical drawings and source code for the software.  Its been on my 'round-to-it' list to get this stuff up on a website sometime.

dwayne

-- Dwayne Reid   <@spam@dwaynerKILLspamspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
http://www.trinity-electronics.com
Custom Electronics Design and Manufacturing

2010\12\22@193648 by Derward Myrick

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Oli,   You may know this but I offer it anyway.

http://groups.yahoo.com/group/Homebrew_PCBs

This group has some good info on making bords your
self at home.  If you have not checked it out you should.

Derward Myrick






{Original Message removed}

2010\12\22@194844 by IVP

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> We had a multi-step cleaning process that we put the raw board
> through before applying the laminate.  Omit any of the cleaning
> steps: reliability went down.  Do all of the steps: the photo
> exposure gauge that we used said that we were getting something
> like 6 micron resolution on the copper.  Every time.
>
> Yeah - Riston film really is that good.

Thanks Dwayne. That's very encouraging. As I say, my very
good and, most importantly, amenable and experienced, friend is
a commercial laminator and has all the gear. Hot and cold rollers,
vacuum table, everything. All I need to get is the film and board

Jo

2010\12\23@035212 by Oli Glaser

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On 23/12/2010 00:36, Derward Myrick wrote:
> Oli,   You may know this but I offer it anyway.
>
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> This group has some good info on making bords your
> self at home.  If you have not checked it out you should.
>
> Derward Myrick
>

Thanks Derrick - just checked it out.
I don't actually make that many but am certainly interested in the process, and there looks to be plenty of good discussions/info there e.g. stuff like doing proper plated through holes. Will probably join up and keep an eye on events there.
I would love to find a quick way of doing multilayer boards some day.. :-) (sure I'm not the only one...)

2010\12\23@040023 by Oli Glaser

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On 22/12/2010 17:28, V G wrote:
> On Tue, Dec 21, 2010 at 6:40 PM, Oli Glaser<KILLspamoli.glaserKILLspamspamtalktalk.net>  wrote:
>
>> With the subject of home or in-house produced PBCs coming up the other
>> day, I thought I would post these pictures I found of a little board I
>> did a while back, just in case anyone is interested (or maybe thinks
>> this kind of stuff is impossible)
>> The footprint is a 0.4mm pitch, 64 pin, QFN (tracks are down to 0.2mm IIRC)
>> Sorry the quality is so bad but hopefully one can get the general idea
>> (it was taken with a phone camera through a loupe as my decent camera
>> charger was broken at the time.. :-)  )
>> Unfortunately I have no pics of the board after it was populated (it
>> worked okay though), and I can't locate the board (if I do I will post a
>> pic)
>>
>> s740.photobucket.com/albums/xx46/oliglaser/
>>
>>
> Beautiful results. I'll probably stop doing toner transfer and do the photo
> resist method.

Thanks :-)
I would recommend it, bit easier/less effort to produce good results IMHO.
With a half decent UV box and a decent cartridge for your printer (nice black lines) you should do fine (just shout if you need any advice though)


2010\12\23@045205 by alan.b.pearce

face picon face
> I would like to try the photoresist method sometime, too. Isn't it
> more expensive than the toner transfer method, though? (As far as the
> cost per-board, and also having to build the UV lightbox..).

I would be tempted to try one of those stereo lithograph printers that polymerise a liquid using UV light, but instead use the UV laser to expose a photoresist. I suspect it could probably be done by making the printing machine think it is printing a single layer thick object, so it does only one pass.
-- Scanned by iCritical.

2010\12\23@045517 by alan.b.pearce

face picon face
> On 22/12/2010 22:55, Mark Rages wrote:
> > On Tue, Dec 21, 2010 at 5:40 PM, Oli Glaser<RemoveMEoli.glaserTakeThisOuTspamtalktalk.net>  wrote:
> >> Unfortunately I have no pics of the board after it was populated (it
> >> worked okay though), and I can't locate the board (if I do I will post a
> >> pic)
> > That's the problem with these small parts: they make the board easy to lose.
> >
>
> Lol, though it probably has more to do with my organisational skills (or
> lack of them) :-)
> It's probably lurking in the back of drawer somewhere... (or sometimes I
> just chuck them if they will have no future use)
> That is a problem with electronics though - so many tiny little parts to
> keep track of...

Yeah, when you find it, you will probably find all those lost single socks keeping it company.
-- Scanned by iCritical.

2010\12\23@051238 by Joe P. Farr

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You can also make your own UV box using LEDs.


www.techbites.com/20090923572/myblog/articles/z001c-a-led-ultra-v
iolet-uv-pcb-exposure-unit.html



From: Derward Myrick [spamBeGonewdmyrickspamBeGonespamearthlink.net] Sent: 23 December 2010 00:46
To: Joe P. Farr
Subject: Re: [EE] Home etched PCBs


Oli,   You may know this but I offer it anyway.

http://groups.yahoo.com/group/Homebrew_PCBs

This group has some good info on making bords your
self at home.  If you have not checked it out you should.

Derward Myrick






{Original Message removed}

2010\12\23@074821 by Olin Lathrop

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Dwayne Reid wrote:
> Keep in mind that laminating the film to the PCB stock takes some
> work unless you have specialized laminating equipment.

I have no idea what is available today.  The last time I etched my own PC
boards was in 1981, but back then you could get photoresist you could paint
on.  It came in two parts, and could be stored normally until mixed.  After
mixing it was light sensitive, so you only mixed up what you needed at the
time.  I think the resist was called "Resolve" or something like that.
Maybe it or something similar is still around today.

Like anything, it took a little experimentation and practise, but it wasn't
hard to get the resist on the board and dry it.  Then you exposed it, washed
off the unexposed resist with water, baked the result, and etched the board..
I made contact masks of the etch pattern with Kodalith sheet film, and found
various exposure techniques to work, including about 20 minutes in sunlight..

Among other things, I made a temperature controller for a photographic water
bath that way.  It worked really well, and no PICs or other programmable
parts were molested in the process.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

2010\12\23@095125 by Oli Glaser

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On 23/12/2010 09:55, TakeThisOuTalan.b.pearceEraseMEspamspam_OUTstfc.ac.uk wrote:
> Yeah, when you find it, you will probably find all those lost single socks keeping it company.

No, they never reappear - all destined for the "sock" black hole (discovered by Hawking in the 80s) somewhere in the centre of the galaxy, thus maintaining the delicate state of equilibrium in the universe...

2010\12\23@102517 by Philip Pemberton

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On 23/12/10 12:49, Olin Lathrop wrote:
> Among other things, I made a temperature controller for a photographic water
> bath that way.  It worked really well, and no PICs or other programmable
> parts were molested in the process.

A dual opamp chip, a thermistor and a potentiometer, then?

-- Phil.
RemoveMEpiclistspamTakeThisOuTphilpem.me.uk
http://www.philpem.me.uk

2010\12\23@104432 by Kerry Wentworth

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Or maybe an LM3911?

Kerry


Philip Pemberton wrote:
{Quote hidden}

-- Internal Virus Database is out-of-date.
Checked by AVG Anti-Virus.
Version: 7.0.289 / Virus Database: 267.11.13 - Release Date: 10/6/05

2010\12\23@121956 by Olin Lathrop

face picon face
Philip Pemberton wrote:
>> Among other things, I made a temperature controller for a
>> photographic water bath that way.  It worked really well, and no
>> PICs or other programmable parts were molested in the process.
>
> A dual opamp chip, a thermistor and a potentiometer, then?

Thermistor (actually 2 in series at opposite sides of the water bath) and
potentiometer, yes.  Then a comparator, divide by 64 binary counter, and
flip-flip.  The comparator produces a output indicating whether the
temperature is above or below the set point.  The counter divides the power
line frequency to roughly 1Hz, which is used to latch the comparator output
in the flip-flop.  The flop-flop output drives a relay that switches a off
the shelf immersion heater on or off.  Today all the logic could be replaced
by a single 10F202, but that wasn't a option back in 1980.

There also a fishtank pump to keep the water circulating, but that is not
part of the temperature control system.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

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